<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title>菜单</title>
		<style type="text/css">
			ul{
				list-style: none;
			}
		</style>
		<script type="text/javascript" src="/js/jquery.min.js"></script>
	</head>
	
	<body style="background-color:greenyellow;">
		<ul>
			<li>
				<a href="#" id="a1" style="text-decoration: none">菜单信息</a>
				<ul id="u1" style="display: none">
					<li>
						<a href="/singer" target="center" style="text-decoration: none">歌手管理</a>
					</li>
					<li>
						<a href="/song" target="center" style="text-decoration: none">歌曲管理</a>
					</li>
				</ul>
			</li>
		</ul>

	</body>
	<script>
		$(function(){
			$("#a1").click(function(){
				if($("#u1").is(':hidden')){
					// alert("显示")
					$("#u1").show();

				}else{
					// alert("隐藏")
					$("#u1").hide();
				}
			})
		});
	</script>

</html>